1. Field of the Invention
This invention relates generally to circlips and apparatus incorporating circlips for connecting two components.
2. Description of the Prior Art
Circlips are used in many engineering applications to inhibit relative axial displacement of two components one of which is at least partially received within the other. FIG. 1 of the accompanying drawings shows a schematic cross-section through part of an assembly incorporating a conventional circlip. Here, the circlip is shown mounted in the mouth of a cylinder 2 for attaching the cylinder to a cylinder base 3 having a radial flange 4 which is received in the cylinder mouth. As illustrated, the circlip is rectangular in transverse cross-section, and its outer diameter edge is received in an annular groove 5, of rectangular cross-section, in the interior surface of the cylinder mouth. For this internal circlip configuration, the circlip is fitted by slipping the circlip over the end of the male, base portion 3, and compressing the circlip radially to allow the circlip to move past the internal lip of the cylinder mouth to register with the annular groove 5, whereupon the circlip springs outwardly into the groove 5. The ends of the circlip adjacent to the discontinuity may be provided with inwardly projecting "ears" having holes to enable installation and removal using circlip pliers for example. Such "eared" circlips (whether internal or external type) cannot be keystoned and are not therefore self-locking. Earless types of circlip may be keystoned, by providing an abutment shoulder (as indicated by the broken line in the figure) on the male portion 3 of the assembly. In both cases, however, since the major transverse dimension of the circlip is disposed radially, significant radial clearance is required for installation and removal.
In the arrangement shown, the central longitudinal axis of the assembly is indicated by the dash-dotted line. In the assembled state, the circlip 1 inhibits relative axial displacement of the components 2,3 against the action of an axial force F in the direction of the arrow in the figure, for example due to pressure of gas in the cylinder. It can be seen that the circlip operates in shear, with the plane of its reaction surfaces generally at 90.degree. to the force which the circlip is resisting. Under continuous, high axial load, the circlip can deform to shallow conical form. Differential coefficients of expansion of the male and female portions (or uneven heating of materials with the same expansion coefficient) can cause relative radial displacement of the male and female components resulting in increased conic deformation of the circlip due to the increased moment. This situation is illustrated in FIG. 2 of the drawings. In this situation, pressure on the circlip is increased significantly since the load is applied to the circlip along the contact edges shown as points P in cross-section. The change of loading on the circlip during operation of the assembly is therefore substantial. Moreover, for the assembly to restore itself as the cylinder 2 contracts radially with reducing temperature, the work done against applied axial force for the edge P of the cylinder to ride up the inclined upper surface of the circlip in the figure is also significant. Even when the assembly reverts to its original temperature, the continuation of axial load, and the circlips conical inclination to the plane of restoration, can mean that, instead of restoration, racking loads lead to increased tensile load in the female component and increased compressive load in the male component.
The problems described above are common to both internal and external circlips and are exacerbated at large component diameters and for components with large expansion differentials These constraints mean that, for large diameter components and high axial loads, such as occur in a Stirling engine for example. conventional circlips are entirely unsuitable. The conventional alternative of fixing components with a ring of bolts also has numerous drawbacks such as high costs. potential access problems, and less than 360.degree. pressure bearing.